There is such a thing as reproductive coercion in abusive relationships. It didn't seem like mom wanted the pregnancy either from what I recall. Or maybe she did but then became depressed because her marriage or the person she fell in love with ended up being completely different.
It wasn't explicitly stated but from the many toxic abusive relationships I read, it probably went like this, the father want to tie down the mom to his side. She struggles so he locked her up and got her pregnant, that way, she won't struggle anymore because she has Jihwan. And from the flashbacks, it worked. That is, until she committed suicide.
So the father and the mother probably doesn't want any children but the father want to tie her down with a child, and after the mom died, he continued to provide for Jihwan because he's "responsible".
I could be wrong though.
I don't think the father told the secretary/driver, he just knows his employer because he works for him since foreover, prb saw all the signs. In many K-drama, personal secretaries are from family's close to the rich household. The young master's be friend with a kid from less rich family since childhood, then they grew up to become subordinate and boss.
Hey does anyone have an inkling as to what the bodyguard meant when he said he didn’t want a kid? Didn’t the mom say that the dad forced her to have the kid? It’s weird the dad told the bodyguard of all people that he didn’t want him. It’s useless for the bodyguard to know and even more useless for the bodyguard to include that detail to MC. So I’m guessing it’s an important detail to the mom’s backstory